/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.apache.causeway.core.metamodel.facets.propparam.specification;

import org.apache.causeway.applib.spec.Specification;

public class SpecificationRequiresFirstLetterToBeUpperCase implements Specification {

    @Override
    public String satisfies(final Object obj) {
        if (!(obj instanceof String)) {
            return null;
        }
        final String str = (String) obj;
        if (str.length() < 0) {
            return "Must contain at least one letter";
        }
        final char firstLetter = str.charAt(0);
        return Character.isUpperCase(firstLetter) ? null : "Must start with upper case";
    }

}
